Introduction: Number of occlusal contacts and uniform bite force distribution during maximum intercuspation are determinants of a good functional occlusion. Distribution of posterior contacts in the three malocclusion groups along with force distribution has been a topic of research. Aim: To quantify the number of occlusal contacts and areas, bite force distribution in Angle’s Class I, II, III subjects using T-scan and to identify the centre of force trajectory. Materials and Methods: This cross-sectional, observational study was conducted in the Department of Orthodontics, SRM College, Chennai, Tamil Nadu, India, from June 2018 to December 2018. Total 45 subjects in the age group of 18 to 24 years were divided into three groups of 15 subjects each based on Angle’s classification of malocclusion with teeth in normal line of occlusion. T-Scan system sensor and software were used to record and store data. The collected data were analysed with IBM Statistical Package for the Social Sciences (SPSS) software version 23.0. The descriptive statistics were performed, followed by Analysis of Variance (ANOVA). Post hoc Tukey test was done to find the difference between the groups. Chi-square test was done for the categorical data and the Paired t-test for determining the significant difference between the bivariate samples in paired groups. Level of significance was set at p<0.05. Results: Out of three study groups, mean contact points (p<0.001), contact areas (p<0.001) and bite forces (p=0.0032) were statistically highly significant in Angle’s class I group when compared to the other groups. Statistically, the right and the left side differences in force distribution of the three groups were significant with the forces predominantly being higher on the right side. Conclusion: Subjects with Angle’s Class I molar relation had greater contacts, contact area and better bite force distribution. There was preference to the right side in bite force distribution in all the three groups. Centre of force trajectory was concentrated between first and second molars in all the groups

Introduction: Grape Seed Extract (GSE) contains Proanthocyanidins (PA) which have been shown to cross-link and strengthen demineralised dentin collagen. There is paucity of research to evaluate if grape seed extract increases the shear bond strength of orthodontic resin when bonding to enamel. Aim: To evaluate the shearbond strength and Adhesive Remnant Index (ARI) scores of enamel surface bonded with orthodontic resin after immersing in 30% of grape seed extract and compare the same with that of control group. Materials and Methods: In this in-vitro study, 72 extracted teeth samples were divided into two groups. The two groups, each with 36 specimens, included Group I (Control), Group II (Test). Teeth in the test group were soaked in 30% grape seed extract for 10 minutes before bonding and teeth in the control group were bonded directly without soaking in grape seed extract. Shearbond strength were measured using a Universal testing machine. To evaluate the amount of resin left on the enamel surfaces after debonding, ARI scores were used. The samples were subsequently evaluated using Scanning Electron Microscope (SEM) to study the surface characteristics of enamel after immersion in grape seed extract. Student t test was used to assess the difference between two groups in shear bond strength and Chi-square test was used for ARI scores. Results: Total of 72 teeth were analysed, 36 extracted teeth in each group. The mean shearbond strength in Group I was 78.9 Newton (N), 59.03 N in Group II. There was a stastistically significant differences in the mean scores of shearbond strength between the groups (p-value=0.0024). The shearbond strength of control group was significantly higher than the Test group. Significant difference(p-value=0.016) found in ARI scores between the two groups. In SEM analysis after grape seed extract conditioning followed by acid etching, pronounced cobble stone appearance was noticed indicating a type II etching pattern. Conclusion: Adhesive failure occurred at the resin and bracket interface indicating that shear bond strength reduces when teeth were immersed in Grape Seed Extract.

Objective: The aim of this study was to evaluate the initial reaction of nasomaxillary complex to protraction force using electronic speckle pattern interferometry (ESPI). Materials and methods:The experiment was done on a dry human skull. Orthopedic protraction forces were applied bilaterally at two different levels; one at the occlusal level and the other at about 15 mm above the occlusal plane and the bone response was studied at two different parameters for each point of force application, namely reactions at 0° angulation and 20° downward to the occlusal plane and to two different force magnitudes of 10 ounces (280 gm) and 16 ounces (453.6 gm). The tests were repeated after expansion and the bone response patterns were compared with preexpansion patterns. Results:The results showed that when a protraction force was applied at the occlusal level, maxilla underwent anterior displacement and counterclockwise rotation. Maxilla underwent pure translation without rotational component when the protraction force was applied at 15 mm above the occlusal plane at an angle of 20° downward to the occlusal plane with activation of the rapid expansion screw by quarter turn. The image obtained during translation was used to locate the center of resistance of nasomaxillary complex. Conclusion:The study highlighted the importance of expanding the maxilla prior to or during the application of protraction force. ESPI is a valuable tool in the evaluation of initial bone response following orthopedic traction in orthodontics.

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